Tubular heater



June 12, 1934.

N. W. THOMPSON TUBULAR HEATER Filed Nov. 10, 1951 Invenjo r: Nelson W.Thom By his Attqrngy Patented June 12, 1934 PATENT OFFICE TUBULAR HEATERNelson Wamsley Thompson, Oakland, Calif., as-

signor to Shell Development Company, San Francisco, Calif., acorporation of Delaware Application November 10, 1931, Serial No.574,234

9 Claims. (01. 122-356) My invention relates to the tubular heatershaving a radiant heat zone vand a convection zone and although'notlimited thereto is more particularly intended for tubular heaters usedfor heating or cracking of hydrocarbon oils.

One object of my invention is to provide efficient and economical meansfor applying intense heat under easy control to hydrocarbon oils for thepurpose of altering their physical and/or chemical character, whilepreventing the combustion gases, on their path to the convection zonefrom dangerously approaching and overheating the bank of tubes in theradiant heat zone.

Another object of my invention is to provide 5 the heater with simplearched crosswalls in the radiant heat zone to support the tubes and tostrengthen the long walls of the heater.

This invention accordingly consists in the features of construction andthe arrangement and 29 design of the parts, which will be more fullyindicated in the following description and claims.

In order to disclose more completely this in- .vention reference is hadto the accompanying drawing showing in Fig. 1 a sectional view of mytubular heater. 1 In the drawing, 1 is the front wall of the heater; 2is a crossarch; an air preheater 3, having a vertical partition 4, isbuilt in in the furnace; air is admitted in front through an opening 5and passed back and forth through the preheater and via the metalenclosure 6 to the burner 'l. The combustion gases are conductedhorizontally through the radiant heat zone 8, towards the back wall 9 ofthe furnace, where the downdraft causes them to pass between theair-preheater 3 and the backwall 9 away from the radiant heat tubes. Thecombustion gases then pass through the arch 10 into the convection zone11, where they come in direct contact with the bank of tubes 12, andfrom where they flow into the flue 13 and to the stack 14. The radiantheat tubes 15 are supported at their ends by the side walls of theheater of which the drawing shows the one sidewall 16 in the background.The radiant tubes 15 are further supported at one or more intermediatepoints by rollers 1'1 positioned upon the crossarches 2, whichcrossarches at the same time brace the front and rear wall of theheater.

Buckstays 18 connected at the top by cross beams 19 prevent the frontand rear walls from bulging. The radiant heat tubes are covered at thetop by a roof of tile 20 suspended from the cross beams 19.

One of the advantages of my invention resides in protecting the radianttubes from being-impinged by flame, locally overheated and bumed outwith disastrous consequences. The radiant tubes are at a safe distancefrom the combustion gases at 8, which are led horizontally across thefurnace, and further in a downward direction to the convection zone awayfrom ,the radiant tubes.

Another advantage resides in the method of supporting the radiant tubesat. intermediate points between the ends by crossarches. This eliminatesthe difficult, expensive, and unsatisfactory method of suspending thesetubes from the roof or of supporting them by special expensive heatresistant beams across the furnace. It further allows the use of longtubes in the radiant zone, keeping the span between two supportingpoints well within the limits of safety. The use of extra long tubesdecreases the number of return bends which in turn decreases thepressure loss through the coil, which results in a more economicaloperation. Furthermore, by supporting the bank of tubes on rollerspositioned in troughs placed on top of the supporting crossarches thewhole bank of radiant heat tubes is made of the full-floating type andis able to freely expand lengthwise. This will prevent the buildso ingup of stresses across the supporting walls in the axial direction of thetubes, which might be disastrous. Asecond function of the crossarches isthe reinforcement obtained for the front and back walls, by balancingthe action of the buck- 5 stays, which will prevent the walls fromcaving in and bulging with the unavoidable consequence of weakening andleakage due to formation of cracks.

I claim as my invention:

1. Fluid heating apparatus comprising: in combination, a horizontalradiation combustion zone, means for effecting combustion within saidzone, a downward gas passage from the radiation zone to a convectionzone for deflecting combustion gases from the top of the radiation zone,an air conduit interposed between said zones and delivering air directlyto the burners, said radiation zone being positioned directly above theconvection zone, a multiplicity of tubular elements within said zonesproviding flow paths for the fluid to be heated, a number of saidelements being positioned within the radiation zone off the generaldirection of flow of the burning gases, the other portion of saidelements being placed in the convection zone and in the path of thecombustion gases.

2. Fluid heating apparatus comprising: incombination, a radiationcombustion zone, means for effecting combustion within said zone, adownward gas passage from the radiation zone to a convection zone fordeflecting combustion gases from the top of the radiation zone, an airconduit interposed between said zones and delivering air to the burners,said radiation zone being positioned directly above the convection zone,a multiplicity of tubular elements within said zones providing flowpaths for the fluid to be heated, a number of said elements beingpositioned within the radiation zone off the general direction of flowof the burning gases, and freely supported by arched cross-wallssubstantially not obstructing said flow and which reinforces two wallsof the apparatus, the other portion of said elements being placed in theconvection zone and in the path of the combustion gases.

3. Fluid heating apparatus comprising: in combination, a radiationcombustion zone, means for effecting combustion within said zone, adownward gas passage from the radiation zone to a convection zone fordeflecting combustion gases from the top of the radiation zone, an airconduit interposed between said zones and delivering air to the burners,a multiplicity of tubular elements within said zones providing flowpaths for the fluid to be heated, a number of said elements beingpositioned within the radiation zone off the general direction of flowof the burning gases and resting upon roller-like members, supported byarched cross-walls substantially not obstructing said flow, the otherportion of said elements being placed in the convection zone and in thepath of the combustion gases.

4. Fluid heating apparatus comprising: in combination, a horizontalradiation combustion zone and separated therefrom a convection heatingzone positioned directly below said radiation zone, an air conduitinterposed between said zones, a downward gas passage from the radiationzone to the convection zone for deflecting combustion gases from the topof the radiation zone, a means for eifecting combustion within theradiation zone, a series of heating tubes within the radiation zonedisposed substantially without the path of the combustion gases andanother series of heating tubes within the convection zone.

5. Fluid heating apparatus comprising: in combination, a horizontalradiation combustion zone and a horizontal convection heating zonepositioned directly below said radiation zone, an air conduit interposedbetween said zones, a downward gas passage from the radiation zone tothe convection zone for deflecting combustion gases from the top of theradiation zone, a means for effecting combustion within the radiationzone, a series of heating tubes within the radiation zone disposedsubstantially without the path of the combustion gases and anotherseries of heating tubes within the convection zone.

6. Fluid heating apparatus comprising: in combination, a radiationcombustion zone, a convection zone and a gas passage from the radiationzone to said convection zone, said radiation zone being positioneddirectly above said convection zone, an air conduit interposed betweensaid zones, a series of heating tubes in said zones and one or morearched cross-walls in the radiation zone for freely supporting the tubeswhile reinforcing two walls of the apparatus.

7. Fluid heating apparatus comprising: in combination, a radiationcombustion zone having a series of heating tubes arranged along one sidethereof, a burner, acombustion gas exit passage at the side of the zoneopposite to the tubes and away from the burner, allowing to divert thecombustion gases away from the tubes and to direct them to a convectionzone positioned directly below said radiation zone and an air conduitinterposed between said zones.

8. In a furnace provided with heating tubes and a cross-wall, atube-supporting means which comprise rollers supported by the cross-wallin direct supporting contact with the tubes, said cross-wall reinforcingtwo walls of the furnace.

9. Fluid heating apparatus comprising in combination, a radiationcombustion zone, aconvection zone and a gas passage from the radiationzone to said convection zone, said radiation zone being positioneddirectly above the convection zone, an air conduit interposed betweensaid zones, a series of heating tubes in said zones and one or morearched cross-walls in the radiation zone for supporting side walls ofthe apparatus and provided with rollers for slidably supporting tubeswithin the radiation zone.

NELSON WAMSLEY THOMPSON.

